Electromagnetic pulse counter

ABSTRACT

An electromagnetic pulse counter having successively operable, contact-operating armatures. The armatures are movable to a rest position, an intermediate position and an active position between the main pole and the secondary pole of a magnetic circuit.

United States Patent Fischer ELECTROMAGNETIC PULSE COUNTER Inventor: Othmar Fischer, Modling, Austria International Standard Electric Corporation, New York, NY.

Filed: Apr. 13, 1970 Appl. No.: 27,676

Assignee:

Foreign Application Priority Data Apr. 18, 1969 Austria ..A 3751/69 U.S.Cl ..335/l19,317/140,335/138, 335/207, 335/265, 335/276 Int. Cl. ..H0lh 51/08 FieldoiSearch ..335/ll9,138,163,l83,207, 335/229, 232, 265, 270, 274, 276; 317/140 m 1 3,643,186 1 1 Feb. 15,1972

[56] References Cited UNITED STATES PATENTS 3,274,524 9/1966 Magida et a1. ..335/183 X 3,198,995 8/1965 Grebe 335/274 X 3,087,030 4/1963 Shebanow.. 335/163 X 2,935,583 5/1960 Howell ..335/207 3,246,096 4/1966 Jacobson ...335/138 X 2,736,845 2/1956 Arthur ..335/270 X Primary Examiner-A. D. Pellinen Attorney-C. Cornell Remsen, Jr., Walter J. Baum, Percy P. Lantzy, J. Warren Whitesel, Delbert P. Warner and James B. Raden [5 7] ABSTRACT An electromagnetic pulse counter having successively operable, contact-operating armatures. The armatures are movable to a rest position, an intermediate position and an active position between the main pole and the secondary pole of a magnetic circuit.

20 Claims, 8 Dravn'ng Figures PATENIEUFEM 1912 SHEET 2 [IF 3 PAI'ENTEDFEB 1 s 1972 3.643.186

SHEET 3 OF 3' FIG. 6

ELECTROMAGNETIC PULSE COUNTER This invention relates to an electromagneticpulse counter, in which successively operable, contact-operating armatures are provided, which are movable to a rest position, an intermediate position, and an active position between the. main pole and the secondary pole of a magnetic circuit.

Such electromagnetic pulse counters are known, e.g., from the Austrian Pat. No. 191,943, in which such pulse counter is described, in which the several annatures are operable in suc- 'cession and those armatures which have not yet been operated are held during the preceding control pulses by the secondary pole, acting as a holding-back pole, and in the pulse intervals are mechanically moved by the previously attracted armature to an intermediate position, which is nearer to the attracting main pole. When an armature has been moved individually to that intermediate position, it can be attracted by the attracting pole in response to the pulse associated with that armature and during that operation imparts an initial stress to a return spring for the next following armature so that the latter is moved to the primed or intermediate position during the following pulse interval.

It is an object of the present invention to provide an electromagnetic pulse counter, in which successively operable, contact-operating armatures are provided, which are movable to a rest position, an intermediate position and an active position between one or more main poles and one or more secondary and/or auxiliary poles of a magnetic circuit, which pulse counter can preferably be incorporated in printed circuit boards. Such electromagnetic pulse counter should be as compact, small, and light in weight as possible, as insensitive as possible to interfering fields, enable the use of armature contacts in a protecting tube and a control by semiconductor devices, such as transistors, have a stray field which is as small as possible, and require only a minimum electric controlling power.

This object is accomplished by the invention in that the magnetic circuit is formed by an axially extending core, which conducts magnetic flux and carries at least one winding, a shell, which conducts magnetic flux and surrounds said core, and a yoke, which is, e.g., platelike and conducts magnetic flux between the shell and core, the magnetic flux-conducting armatures, which close the magnetic circuit and operate the contacts extend radially, e.g., in a starlike array, between the core and shell and between the main pole or poles and the secondary and/or auxiliary pole or poles in the magnetic circuit, and the magnetic flux is divided between the main pole or poles and the secondary and/or auxiliary pole or poles in accordance with the distribution of the reluctances in the magnetic circuit.

The provision of a central core, which carries at least one winding and which is included in a magnetic circuit that is closed by the shell, yoke and armatures, which extend radially, e.g., in a starlike array, and includes one or more main poles and one or more secondary and/or auxiliary poles, and the provision of contact sets and priming spring sets which extend radially, e.g., in astarlike array, around the central core, as distinguished from the linear arrangement of the armatures, contact sets and priming spring sets in the known pulse counter, affords in a simple manner the advantages of a compact, small, lightweight structure, which has a small stray field, is insensitive to interfering fields, has a low control power requirement, and ensures that the size and weight of the counter are such that it can be accommodated on a printed circuit board, where the electric circuits can be connected to the conductors by soldered or plugged joints, e.g., by a base and holder, as in the case of electron tubes.

In a development of the invention, the armatures operate priming springs so that the operation of an armature by one control pulse causes that armature which is to be operated in response of the next control pulse to move away from the secondary pole tending to hold said armature in its rest position toward the main pole for attracting the armature in response to the next control pulse.

In' a further development of the invention, the operation of the individual contacts proceeds in the clockwise or counterclockwise sense around the central core.

In another embodiment of the invention, the core carries an attracting winding and a throwoff winding, which when energized establishes a magnetic field acting to restore attracted armatures to their rest position.

In a development of the invention, a predetermined armature assumes its intennediate position when all armatures have been thrown off. I

In a desirable embodiment of the invention, the pulse counter is provided with 10 or I l or 12 or l6 or any desired number of armatures and of contact sets operable by said armatures. I

In a further embodiment of the invention, the contact sets and/or priming spring sets extend parallel to the generatrix of the shell.

In another embodiment of the invention, the contact sets and/or priming spring sets extend radially, e.g., in a starlike array, in one or more planes which is or are parallel to the plane of the armatures.

In a development of the invention, each contact set and/or priming spring set is disposed between two of the armatures.

In another embodiment of the invention, one or more of the contact sets comprise additional contacts, which are operable by the armatures and serve, e.g., to indicate a predetermined count.

Another embodiment of the invention is characterized by the provision of additional contact sets, which are operable when the armatures associated with these contact sets move from the position of rest to the intermediate position and/or from the intermediate position to the active position.

In another embodiment of the invention, an additional armature is provided, which is attracted or drops out to operate contacts in response to each control pulse.

In a further embodiment of the invention, the contact sets consist of armature contacts contained in a protecting tube and operable by permanent magnets.

In another embodiment of the invention, the armatures carry the permanent magnets for operating the armature contacts, or magnetic shields, which in dependence on the position of the armatures enable or inhibit an action of the magnetic field of stationary permanent magnets on the associated armature contacts to operate the same.

In a development of the invention, adjacent armatures carry permanent magnets of opposite polarity.

In an embodiment of the invention, the armatures made of magnetic flux-conducting material consist of. parts which are resiliently deformable under the action of the magnetic field, or of rigid parts, whichare movable about a bearing, e.g., the edge of the shell. I

In a special embodiment of the invention, the core carries the main pole or poles and the secondary pole or poles and the armatures are movably mounted on or fixed to the shell. In another embodiment, the shell carries the main pole or poles and the auxiliary pole or poles and the armatures are movably mounted on or fixed to the core.

In a development of the invention, the magnetic circuit consists of soft magnetic material, into which hard magnetic material, such as one or more ferrite discs, is embedded to control magnetic properties of the circuit, e.g., its remanence.

In an embodiment of the invention, the magnetic circuit consists of soft magnetic material and magnetic properties of the circuit, e.g., its remanence, are determined by windings which are flown through by an auxiliary current so that the armatures move to their rest position, e.g., in response to a removal or reduction of said auxiliary current.

In a special embodiment of the invention, one pulse of each pulse train, e.g., every 16th pulse, acts as a throwoff pulse because the windings or parts thereof are energized or their connections are changed by additional contacts.

In an embodiment of the invention, the shell carries an external winding, by which the-residual axial stray field can be reduced. 5

In another embodiment of the invention, parts of the magnetic circuit consist of electrically nonconducting material which conducts magnetic flux, and electrically conducting parts of the magnetic circuit are used to conduct electric current so that the structure of the pulse counter according to the invention is simplified.

In another embodiment of the invention, parts of the magnetic circuit consist of electrically nonconducting material which conducts magnetic flux and in which parts are embedded which are made'of electrically conducting material and electrically connect the contact springs to the terminal pins and/or have extensions which form terminal lugs or connecting plugs.

In an embodiment of the invention,-parts of the magnetic circuit have electrically conducting parts embedded therein which are electrically insulated from the parts in which they are embedded and electrically connect the contact springs to the terminal pins and/or have extensions formed as terminal lugs or connecting plugs.

In another embodiment of the invention, the leads connected to the contacts extend through bores in the shell, yoke and/or core.

In another embodiment of the invention, the terminals of the windings and contacts consist of terminal lugswhich can be soldered to printed circuit boards, or of connecting plugs.

In an embodiment of the invention, the pulse counter is provided with a dusttight cover cap or in another suitable embodiment, the pulse counter is enclosed in a tight housing, which is filled with a protective gas.

In another embodiment of the invention, the housing of the pulse counter contains semiconductor devices or semiconductor circuits, e.g., transistor circuits, so that the resulting unit can be operated with a relatively small control current;

In an embodiment of the invention, the pulse counter is preceded by semiconductor circuits, which have a differentiating action on the control pulse, and the windings are fed with such control pulses.

In another embodiment of the invention, cooling bodies may be attached for a dissipation of heat.

The pulse counter according to the invention will be described with reference to the drawings, in which one embodiment is shown in FIG. 1 partly in an axial sectional view and in FIG. 2 in a top plan view.

FIG. 3 shows another embodiment partly in an axial sectional view.

FIG. 4, is a top. plan view showing another embodiment.

FIG. 5 is an axial sectional view showing the magnetic circuit of another embodiment.

FIG. 6 shows another embodiment partly in an axial sectional view.

FIG. 7 is a top plan view showing part of another embodiment.

FIG. 8 shows part of an array of armature contacts which are provided in the pulse counter and contained in a protective tube, and the magnets for operating said armatures.

FIGS. 1 and 2 show an embodiment of the pulse counter according to the invention comprising 12 armatures 1 to 12. Two of these armatures, designated 1 and 7, are shown individually, the armature l in its active position, to which it has been attracted by the main pole piece 18, and the armature 7 in its rest position. In the embodiment shown by way of example in FIGS. 1 and 2, each of the armatures l to 12 has two contact sets associated with it, which are operable by the armature. Of these contact sets, contacts 14 and 16 are shown in FIG. 1 and contacts 13,14, 15 and 16 in FIG. 2. In this embodiment of the pulse counter, the contacts which are closed by an operated armature, e.g., thecontact 14'closed by the armature 1, are opened when that armature is operated which is the next in the operating sequence of the pulse counter. In the example which has been selected, this applies to armature 2. The operating sequence is indicated by the arrow. in FIG. 2. Besides, the next contact, which is associated with armature 2 and not shown in FIG. 2, is closed.

The magnetic circuit of the pulse counter is composed of the main core 17 provided with the main pole piece 18, the secondary core 19 with the secondary pole piece 20, the armatures 1 to 12, the shell 21, the yoke 22 and a part 23, which is optionally included in the magnetic circuit, e.g., to determine the remanence of the circuit. The current-carrying coil 24 produces the magnetic flux which causes a primed armature to be attracted.

Armatures 1 to 12 are mounted on an edge 25 of the shell 21. The retaining springs force the armatures against the edge 25 of the shell and thus hold the armatures in position. Owing to the remanence of the magnetic circuit of the pulse counter, the position of each. of the armatures 1-12 is controlled either by the magnetic circuit including the main pole piece 18 or by the magnetic circuit including the secondary pole piece 20. In a manner which is known per se but not shown in FIG. 1, that armature 2 which is to be operated next is in an intermediate position between the 1 secondary pole piece 20, acting as a holding-back pole, and the main pole piece 18, acting as an attracting pole. The priming springs, which are not shown in FIG. 1 and known per se, ensure in known manner that the armatures l to 12 will be operated in succession because when an armature has been attracted the next armature in the sequence of operations is primed in that it is moved to the intermediate position between the attracting and holding-back poles during the interval which succeeds the current pulse acting on the winding 24. Those of the annatures l to 12 which have been moved to their active positions in response to one or more control pulses acting on the winding 24 will remain attracted to the common main pole piece 18 until all armatures moved to their active position are returned to their rest position by a magnetization which opposes the main field and is produced by a known throwoff winding, which is not shown in FIG. 1. In FIG. 1, armature 7 is shown in position of rest.

FIG. 3 shows another embodiment, in which the contact sets and the priming spring sets extend radially above the armatures in a plane which is parallel to the plane of the armatures. It will be assumed that this embodiment comprises, e.g., eight armatures, so that the two armatures shown in FIG. 3 are designated 1 and 5. In this embodiment too, each armature has contact sets associated with it, which are operated as the armature is attracted, and arranged so that each armature as it is attracted opens the contact that has been closed when the preceding armature in the sequence of operations was attracted, closes the following contact, and causes the armature which follows in the sequence of operations to be moved to an intermediate position by the priming spring.

For the sake of clearness, the priming spring sets have been omitted in FIG. 3 and only one of the two contact sets are shown which are associated with an armature and operable thereby.

FIG. 3 shows the armature l in its active position and the armature 5 in its rest position. One of the two contact sets operable by the armature 1-this one contact set is designated 26 in FIG. 3was closed when the armature which precedes the armature l in the sequence of operations was operated; this contact set was been opened when the armature l was attracted and for this reason is shown in operated position. The second contact set operated by the armature 1 is not shown in FIG. 3 for the sake of cleamess. Similarly, only one of the two contact sets which are operable by the armature 5 is shown in FIG. 3. This contact set, which is designated 27, is shown in an open position because the armature 5 is in position of rest.

In the embodiment of the pulse counter shown in FIG. 3, the

springs of the contacts and of the priming spring sets are similar to the springs used in the known pulse counter disclosed in the Austrian Pat. No. l9 1 ,943.

In FIG. 3, the armatures consist of parts which are resiliently deformable by the attracting force which is exerted by the main pole piece 18; these parts consist of thin lamina, which are resiliently flexible and firmly gripped at the core 17, or are attached to thin plates, which are resiliently flexible and secured to the core. In the embodiment shown in FIG. 3, the secondary pole 20 is secured to the outside of the shell 21.

The terminals for the contacts consist of terminal pins and extend through an axial bore, which is provided in the core 17 The terminals 35 and 36 for the attracting winding and the throwoff winding, not shown, consist also of terminal pins extending through bores in the yoke 22.

FIG. 4 is a top plan view showing another embodiment of the pulse counter, in which the contact sets and priming spring sets extend radially and are disposed between adjacent armatures. The embodiment shown by way of example comprises eight armatures. The drawing shows the armatures 1, 2, 3, 5, 7 and 8 and the spring sets 28 to 33 of the contact and priming spring sets. When one of the armatures, e.g., the armature 1, is primed to be attracted in response to the next counting pulse, and the operations proceed in the clockwise sense, the armature will close the contact 29 and open the contact 28 and at the same time will move the armature 2 to an intermediate position between the secondary and main pole pieces.

FIG. 5 shows another embodiment of the magnetic circuit of the pulse counter according to the invention, where the secondary pole piece 20 is disposed within the cylindrical shell 21, which carries the main pole piece 18. Just as in the embodiment of FIGS. 3 and 4, the main pole piece 18 and the secondary pole piece 20 are annular. The armatures are not shown in FIG. 5 and are arranged substantially as in FIG. 3 or 4, also the contact sets and priming spring sets. Itwill be understood that the number of contact sets and annatures can be selected as desired.

FIG. 6 shows another embodiment of the pulse counter according to the invention, in which the magnetic circuit is similar to that of the embodiment of FIG. 1 but the contact sets and priming spring sets extend radially over the armatures in a plane which is parallel to the plane in which the armatures are arranged. Two of the armatures are shown in the drawing. The fixation of the armatures to the shell 21 is similar to the fixation of the armatures to the core as described with reference to FIG. 3. The leads for the contacts extend through bores 46 in the shell 21 and are provided with terminal pins 34. The pulse counter of FIG. 6 is similar in function to that described with reference to FIG. 3 so that this operation need not be explained further.

FIG. 7 shows diagrammatically an embodiment which is similar to that of FIG. 6 but has contact sets and priming spring sets which extend radially between adjacent armatures. FIG. 7 shows only three armatures l, 2 and 3, as well as the contact and priming spring sets 47 and 48, which are associated with and operable by the armature 2. In the manner described hereinbefore, contact 47 is closed when armature l is attracted and opened when the armature 2 is attracted. The latter operation causes the contact 48 to be closed and the armature 3 to be moved by the priming spring set to an intermediate position, from which it moves to its active position in response to the next counting pulse. As a result, the contact 48 is opened, the next contact associated with the armature 3 is closed, and the next armature is moved to its intermediate position.

Just as in the embodiment of FIG. 6, the leads connected to the contact springs in the embodiment of FIG. 7 extend through bores 46 in the shell 21.

In another embodiment of the pulse counter, the contact sets consist of armature contacts in a protective tube, which are operable by permanent magnets attached to the armatures. FIG. 8 shows diagrammatically the arrangement of such contact sets 37 to 40, e.g., at the periphery of the shell of a magnetic circuit, not shown, of a pulse counter having annatures corresponding in number to the contact sets and-operable in known manner in the magnetic circuit, which armatures carry permanent magnets for operating the associated armature contacts in such a manner that two permanent magnets secured to adjacent armatures have opposite magnetic polarities. When in such an arrangement one armature, e.g., the armature carrying the magnet 43, is attracted as the next in the pregiven sequence of operation after the previouslyattracted armatures-carrying the magnets 41 and 42, so that the magnet 43 secured to the armature being attracted is moved between the armature contacts 38 and 39, the field of magnet 43 will cause the contact 39 to be closed and will oppose the field of the magnet 42 to open the previously closed contact 38. The attraction of the armature associated with magnet 43 primes in known manner the armature associated with magnet 44 so that the last-mentioned armature will be attracted in response to the next counting pulse. The contacts 37 to 40 will thus be operated in a sequence which is indicated by the arrow in FIG. 8. The permanent magnets 44 and 45 associated with armatures in rest position do not actuate the armature contacts 39 and 40 associated with them unless their armatures are attracted.

This is accomplished, e.g., in that the permanent magnets which are associated with nonoperated armatures are surrounded by a part made of a material which conducts magnetic flux and in which their magnetic field extends so that it does not act on the respective armature contacts.

In another embodiment, the permanent magnets may be stationary and disposed between adjacent armature contacts; in this case, the armatures carry magnetic shields, which in dependence on the position of the armatures enable or inhibit the action of the magnetic field of the permanent magnets to operate the associated armature contacts.

In all embodiments of the pulse counter according to the invention which have been described, armature contacts may be arranged in a protective tube without departing from the scope of the invention.

I claim:

1. An electromagnetic pulse counter, comprising a plurality of contacts, a plurality of successively operable contactoperating armatures, said armatures being movable to a rest position, an intermediate position, and an active position between a main pole and an auxiliary pole of a magnetic circuit, the magnetic circuit being formed by an axially extending core, said core conducting magnetic flux and carrying at least one winding shell which conducts magnetic flux and surrounds said core, and a yoke which is platelike and conducts magnetic flux between the shell and core, the magnetic flux-conducting armatures, which close the magnetic circuit and operate the contacts, extending radially in a starlike array, between the core and the shell and between the main pole and the auxiliary pole in the magnetic circuit, and the magnetic flux being divided between the main pole and the auxiliary pole in accordance with the distribution of the reluctances in the magnetic circuit.

2. An electromagnetic pulse counter according to claim 1, in which the armatures operate priming springs so that the operation of an armature by one control pulse causes that armature which is to be operated in response to the next control pulse to move away from the secondary pole tending to hold said armature in its rest position toward the main pole for attracting the armature in response to the next control pulse.

3. An electromagnetic pulse counter according to claim I in which the operation of the individual contacts proceeds in the clockwise or counterclockwise sense around the central core.

4. An electromagnetic pulse counter according to claim 1 in which a predetermined armature assumes its intermediate position when all armatures have been thrown off.

5. An electromagnetic pulse counter according to claim 1 in which there are provided any desired number of armatures and contact sets operable by said armatures.

6. An electromagnetic pulse counter according to claim 5 in which the contact sets and priming spring sets extend parallel to the generatrix of the shell.

7. An electromagnetic pulse counter according to claim 5 in which each contact set and priming spring set is disposed between adjacent armatures.

8. An electromagnetic pulse counter according to claim 5 in which one of the contact sets comprises additional contacts which are operable by the armatures and serve, e.g., to indicate a predetermined count.

9. An electromagnetic pulse counter according to claim 5 in which additional contact sets are provided and operable when the armatures associated with these contact sets move from the rest position to the intermediate position and/or from the intermediate position to the active position.

10. An electromagnetic pulse counter according to claim in which the contact sets consist of armature contacts which are operable by permanent magnets.

11. An electromagnetic pulse counter according to claim 10, in which the armatures carry the permanent magnets for operating the armature contacts, or magnetic shields, which in dependence on the position of the armatures enable or inhibit an action of the magnetic field of stationary permanent magnets on the associated armature contacts to operate the same.

12. An electromagnetic pulse counter according to claim 10, in which permanent magnets are arranged so that adjacent permanent magnets have opposite magnetic polarities.

13. An electromagnetic pulse counter according to claim 1 in which the core carries the main pole and the secondary pole and the armatures are movably mounted on the shell.

14. An electromagnetic pulse counter according to claim 1 in which the shell carries the main pole and the secondary pole and the armatures are movably mounted on the core.

15. An electromagnetic pulse counter according to claim 1 in which the magnetic circuit consists of soft magnetic material, and in which magnetically hard material, such as one or more ferrite discs, is embedded to control magnetic properties of the circuit, e.g., its remanence.

16. An electromagnetic pulse counter according to claim 1 in which parts of the magnetic circuit consist of electrically nonconducting materials which conduct magnetic flux and in which parts are embedded which are made of electrically conducting materials and electrically connect the contact springs to the terminal pins and/or have extensions which form terminal lugs or connecting plugs.

17. An electromagnetic pulse counter according to claim 1 in which parts of the magnetic circuit have electrically conducting parts embedded therein, which are electrically insulated from the parts in which they are embedded and electrically connect the contact springs to the terminal pins and have extensions formed as terminal lugs or connecting plugs.

18. An electromagnetic pulse counter according to claim 1 including leads connected to the contacts extend through bores in the shell, yoke and core.

19. An electromagnetic pulse counter according to claim 1 in which the contacts terminate in terminal lugs which can be soldered to printed circuit boards.

20. An electromagnetic pulse counter according to claim 1 in which contacts terminate in connecting plugs. 

1. An electromagnetic pulse counter, comprising a plurality of contacts, a plurality of successively operable contact-operating armatures, said armatures being movable to a rest position, an intermediate position, and an active position between a main pole and an auxiliary pole of a magnetic circuit, the magnetic circuit being formed by an axially extending core, said core conducting magnetic flux and carrying at least one winding shell which conducts magnetic flux and surrounds said core, anD a yoke which is platelike and conducts magnetic flux between the shell and core, the magnetic flux-conducting armatures, which close the magnetic circuit and operate the contacts, extending radially in a starlike array, between the core and the shell and between the main pole and the auxiliary pole in the magnetic circuit, and the magnetic flux being divided between the main pole and the auxiliary pole in accordance with the distribution of the reluctances in the magnetic circuit.
 2. An electromagnetic pulse counter according to claim 1, in which the armatures operate priming springs so that the operation of an armature by one control pulse causes that armature which is to be operated in response to the next control pulse to move away from the secondary pole tending to hold said armature in its rest position toward the main pole for attracting the armature in response to the next control pulse.
 3. An electromagnetic pulse counter according to claim 1 in which the operation of the individual contacts proceeds in the clockwise or counterclockwise sense around the central core.
 4. An electromagnetic pulse counter according to claim 1 in which a predetermined armature assumes its intermediate position when all armatures have been thrown off.
 5. An electromagnetic pulse counter according to claim 1 in which there are provided any desired number of armatures and contact sets operable by said armatures.
 6. An electromagnetic pulse counter according to claim 5 in which the contact sets and priming spring sets extend parallel to the generatrix of the shell.
 7. An electromagnetic pulse counter according to claim 5 in which each contact set and priming spring set is disposed between adjacent armatures.
 8. An electromagnetic pulse counter according to claim 5 in which one of the contact sets comprises additional contacts which are operable by the armatures and serve, e.g., to indicate a predetermined count.
 9. An electromagnetic pulse counter according to claim 5 in which additional contact sets are provided and operable when the armatures associated with these contact sets move from the rest position to the intermediate position and/or from the intermediate position to the active position.
 10. An electromagnetic pulse counter according to claim 5 in which the contact sets consist of armature contacts which are operable by permanent magnets.
 11. An electromagnetic pulse counter according to claim 10, in which the armatures carry the permanent magnets for operating the armature contacts, or magnetic shields, which in dependence on the position of the armatures enable or inhibit an action of the magnetic field of stationary permanent magnets on the associated armature contacts to operate the same.
 12. An electromagnetic pulse counter according to claim 10, in which permanent magnets are arranged so that adjacent permanent magnets have opposite magnetic polarities.
 13. An electromagnetic pulse counter according to claim 1 in which the core carries the main pole and the secondary pole and the armatures are movably mounted on the shell.
 14. An electromagnetic pulse counter according to claim 1 in which the shell carries the main pole and the secondary pole and the armatures are movably mounted on the core.
 15. An electromagnetic pulse counter according to claim 1 in which the magnetic circuit consists of soft magnetic material, and in which magnetically hard material, such as one or more ferrite discs, is embedded to control magnetic properties of the circuit, e.g., its remanence.
 16. An electromagnetic pulse counter according to claim 1 in which parts of the magnetic circuit consist of electrically nonconducting materials which conduct magnetic flux and in which parts are embedded which are made of electrically conducting materials and electrically connect the contact springs to the terminal pins and/or have extensions which form terminal lugs or connecting plugs.
 17. An electromagnetic pulse counter according to claim 1 in whiCh parts of the magnetic circuit have electrically conducting parts embedded therein, which are electrically insulated from the parts in which they are embedded and electrically connect the contact springs to the terminal pins and have extensions formed as terminal lugs or connecting plugs.
 18. An electromagnetic pulse counter according to claim 1 including leads connected to the contacts extend through bores in the shell, yoke and core.
 19. An electromagnetic pulse counter according to claim 1 in which the contacts terminate in terminal lugs which can be soldered to printed circuit boards.
 20. An electromagnetic pulse counter according to claim 1 in which contacts terminate in connecting plugs. 